The present invention relates to a bipolar high-frequency treatment tool for an endoscope having a pair of high-frequency electrodes which are electrically insulated from each other at a tip end of a flexible sheath of the endoscope.
Generally, an endoscope unit having a bipolar high-frequency treatment tool is provided with a pair of high-frequency electrodes which are electrically insulated from each other at a tip end of a flexible sheath. In such an endoscope, a pair of operation wires to operate the electrodes is arranged to extend in parallel with an axis of the sheath throughout an entire length of the sheath. The pair of operation wires are configured to be advanced forward and retracted backward and are made of an electrically conductive material to conduct electrical currents respectively to the high-frequency electrodes although each of the operation wires are maintained insulated. Examples of such an endoscope unit are disclosed in Japanese Patent Provisional Publication Nos. 2004-57454 and 2005-296304.
In the endoscope units disclosed in the above-references publications, when treatment using high-frequency currents is performed, it is often desired that an orientation of the electrodes with respect to a treatment object is adjusted by rotating the electrodes about an axis of the flexible sheath. In such a case, conventionally, the flexible sheath together with the electrodes is rotated about the axis of the flexible sheath at a proximal end thereof by an operator.
With this operation, however, as the flexible sheath is inserted into an insertion channel of the endoscope which is winding inside a human body, resistance applied to the sheath against inner surfaces of the insertion channel is not constant throughout the length of the sheath and may vary. Therefore, in many cases, a distal end portion of sheath may be rapidly rotated even when a proximal end portion of the sheath is rotated slowly, and vice versa, and in other words, the flexible sheath are often rotated partially and irregularly. Thus, it has been difficult to adjust the orientation of the high-frequency electrodes with respect to the axis of the flexible sheath.